-- CALIFORNIA D EPAUMENT OF cdfa FOOD & AGRICULTURE ~ California Pest Rating Proposal for Meloidogyne incognita (Kofoid & White, 1919) Chitwood 1949 Southern root-knot nematode Current Pest Rating: C Proposed Pest Rating: C Domain: Eukaryota; Kingdom: Metazoa; Phylum: Nematoda; Family: Meloidogynidae Comment Period: 04/08/2021 through 05/23/2021 Initiating Event: Requests for permits to move and use Meloidogyne incognita, southern root-knot nematode, for research purposes have been received by the CDFA Permits and Regulations program. The current rating and status of M. incognita in California is re-evaluated herein, and a permanent pest rating is proposed. History & Status: Background: Root-knot nematodes (Meloidogyne spp.) were first being reported in California by E. A. Bessey in 1911. The name Meloidogyne is of Greek origin, meaning "apple-shaped female." It is one of the most extensively studied groups in the state with six species of significant economic concern: M. incognita, M. javanica, M. arenaria, M. hapla, M. chitwoodi, and M. naasi which was only found from golf courses in few counties of southern California. The host ranges of different species are variable but encompass most of the economically important agronomic and ornamental crops grown in California. The species are distributed widely in California’s agricultural areas but show some regional and crop distribution preferences, with M. incognita being the only species that parasitizes cotton (Chitambar et al., 2018; Dong et al., 2007). There are four host races within M. incognita that can be separated by a host differential test. Meloidogyne incognita races 3 and 4 will reproduce on cotton, whereas races 1 and 2 will not (Kirkpatrick and Sasser, 1984). -- CALIFORNIA D EPAUMENT OF cdfa FOOD & AGRICULTURE ~ Meloidogyne incognita is found worldwide in tropical and subtropical regions, and damage is worse in warmer climates. In California, M. incognita is found more often in the hot valleys of the interior. The effect of root-knot nematodes on plants can be dramatic. As a result of their feeding, large galls or “knots” are formed on the root systems, which impairs the plant’s ability to take up water and nutrients from the soil. The females are globose and sedentary at maturity. They establish a feeding site as juveniles and permanently remain within the plant root, exuding eggs out into the soil. The feeding site is a group of cells known as "giant-cells", created when the nematode injects secretory proteins that stimulate changes within the parasitized cells. The injected cells rapidly become multinucleate when division occurs without cell wall formation. Giant-cells can be very large and act as serious nutrient sinks, producing large amounts of proteins that the nematode can use. Increase in the production of plant growth regulators from nematode feeding also plays a role in this increase in cell size and division. Root cells next to the giant-cells enlarge and divide rapidly, resulting in gall formation. Meloidogyne spp. generally reproduce by mitotic parthenogenesis, meaning that males are not necessary and viable eggs can be produced by females alone in the absence of fertilization. Vermiform males are rare and are only found when the population is subjected to an environmental stress, but they can mate with females. Eggs hatch in the soil and vermiform juveniles (mostly female sometimes male) swim to new roots (Mitkowski and Abawi, 2003). Hosts: Abelmoschus esculentus (okra), A. manihot (bele), Acacia confusa, Achillea millefolium (yarrow), Actinidia deliciosa (kiwifruit), Agave, Albizia lebbeck (Indian siris), Alcea rosea (Hollyhock), Aloe vera (true aloe), Amaranthus (amaranth), A. blitoides (spreading amaranth), A. blitum (livid amaranth), A. deflexus (perennial pigweed), A. hybridus (smooth pigweed), A. spinosus (spiny amaranth), A. viridis (slender amaranth), Anacardium occidentale (cashew nut), Ananas comosus (pineapple), Anchusa azurea (Italian alkanet), Anethum graveolens (dill), Aptenia cordifolia, Arabidopsis thaliana, Araujia sericifera (Arejishi), Areca catechu (betelnut palm), Asparagus officinalis (asparagus), Basella alba (malabar spinach), Bassia scoparia, Bertholletia excelsa (Brazil nut), Beta vulgaris (beet), Bidens pilosa (blackjack), Brassica oleracea (cabbages, cauliflowers), B. oleracea var. gongylodes (kohlrabi), Brassicaceae (cruciferous crops), Calendula officinalis (pot marigold), Canavalia ensiformis (jack bean), Canna, C. indica (canna lilly), Cannabis sativa (hemp), Capsicum annuum (bell pepper), Cardiospermum halicacabum (balloon vine), Carica papaya (pawpaw), Chenopodium album (fat hen), C. murale (nettleleaf goosefoot), Chrysanthemum (daisy), Chicorium (chicory), Citrullus lanatus (watermelon), Cleome viscosa (Asian spiderflower), Clitoria ternatea (butterfly-pea), Cocos nucifera (coconut), Coffea (coffee), C. arabica (arabica coffee), C. canephora (robusta coffee), Colocasia, C. esculenta (taro), Commenlina benghalensis (wandering jew), Convolvulus arvensis (bindweed), Cordia myxa (sebesten), Cordyline fruticosa (ti plant), Coriandrum sativum (coriander), Cucumis anguria (West Indian gherkin), C. melo (melon), C. sativus (cucumber), Cucurbita argyrosperma (silver-seed gourd), C. maxima (giant pumpkin), C. moschata (pumpkin), C. pepo (marrow), Cucurbitaceae (cucurbits), Cullen corylifolium (black-dot), Curcuma alismatifolia, C. longa (turmeric), Cyperus (flatsedge), C. haspan, C. rotundus (purple nutsedge), Dahlia coccinea, Datura metel (Hindu datura), D. stramonium (jimsonweed), Daucus carota (carrot), Digitaria horizontalis, D. insularis (sourgrass), Dioscorea (yam), D. alata (white yam), D. batatas (Chinese yam), D. cayenensis (Guinea yam), D. esculenta (Asiatic yam), D. rotundata, Duranta erecta (golden dewdrop), Echinochloa crus-galli (barnyard grass), Emelia sonchifolia (red tasselflower), -- CALIFORNIA D EPAUMENT OF cdfa FOOD & AGRICULTURE ~ Eragrostis ciliaris (gophertail lovergrass), Eryngium foetidum, Euphorbia heterophylla (wild poinsettia), Euphorbia prostrata, Euphorbia tirucalli (Indian-tree spurge), Fabaceae (leguminous plants), Ficus, F. benjamina (weeping fig), F. elastica (rubber plant), F. religiosa (sacred fig tree), Galinsoga parviflora (gallant soldier), Gazania (treasure-flower), Gloxinia, Gomphrena globosa (globe amaranth), Gossypium (cotton), Helianthus annuus (sunflower), Hemerocallis (daylilies), Hevea brasiliensis (rubber), Hibiscus cannabinus (kenaf), H. syriacus (shrubby althaea), H. trionum (Venice mallow), Ipomoea batatas (sweet potato), I. nil (white ledge morning-glory), I. purpurea (tall morning glory), Jacquemontia pentantha, Jasminum multiflorum (star jasmine), J. sambac (Arabian jasmine), Juglans (walnuts), Kalanchoe fedtschenkoi, Lactuca (lettuce), L. sativa (lettuce), L. serriola (prickly lettuce), Lagenaria siceraria (bottle gourd), Lantana camara (lantana), Lavandula angustifolia (lavender), Lens culinaris subsp. culinaris (lentil), Lotus corniculatus (bird’s-foot trefoil), Luffa acutangula (angled luffa), L. aegyptiaca (loofah), Malpighia emarginata, M. glabra (acerola), Malva pusilla (round-leaved mallow), Mangifera indica (mango), Manihot esculenta (cassava), Medicago sativa (lucerne), Melilotus indica (Indian sweetclover), Mentha spicata (Spear mint), Momordica charantia (bitter gourd), Morinda citrifolia (Indian mulberry), Morus (mulberrytree), M. nigra (black mulberry), Murraya paniculata (orange jessamine), Musa (banana), M. acuminata (wild banana), Musa x paradisiaca (plantain), Nicotiana tabacum (tobacco), Oenanthe javanica, Olea europaea subsp. europaea (European olive), Ophiopogon japonicus, Oryza sativa (rice), Parthenium hysterophorus (parthenium weed), Passiflora edulis (passionfruit), Paulownia elongata (elongate paulownia), Persicaria posumbu, Phaseolus (beans), P. vulgaris (common bean), Phoenix dactylifera (date-palm), Phyla nodiflora, Piper methysticum (kava), P. nigrum (black pepper), Pithecellobium dulce (Manila tamarind), Pittosporum tobira (Japanese pittosporum), Platago lanceolata (ribwort plantain), Polianthes tuberosa (tuberose), Polygonum aviculare (prostrate knotweed), Pongamia pinnata (Indian beech), Portulaca oleracea (purslane), P. quadrifida (chickenweed), Prosopis juliflora (mesquite), Prunus (stone fruit), P. domestica (plum), P. persica (peach), Psophocarpus tetragonolobus (winged bean), Ptychosperma elegans (solitaire palm), Punica granatum (pomegranate), Radermachera sinica, Rhaponticum repens (Russian knapweed), Rollinia mucosa, Rosmarinus officinalis (rosemary), Rumex acetosa (sour dock), Saccharum officinarum (sugarcane), Samanea saman (rain tree), Sansevieria trifasciata (mother-in-law’s tongue), Schinus terebinthifolius (Brazilian pepper tree), Sesamum indicum (sesame), Setaria viridis (green foxtail), Sida rhombifolia, Sinapis alba (white mustard), Solanaceae, Solanum americanum, S. lycopersicum (tomato), S. melongena (aubergine), S. nigrum (black nightshade), S. sisymbriifolium, S. tuberosum (potato), Spinacia oleracea (spinach), Tabebuia serratifolia, Tagetes erecta (Mexican marigold), Tephrosia vogelii (Vogel’s tephrosia), Trachyspermum ammi, Veitchia merrillii (Christmas palm), Vernonia cinerea, Vigna angularis (adzuki bean), V. mungo (black gram), V. radiata (mung bean), V. unguiculata (cowpea), Viola pilosa, Vitex agnus-castus (lilac chastetree), V. trifolia, Vitis vinifera (grapevine), Washingtonia robusta (Mexican fan palm), Xanthosoma (cocoyam), Zea mays (maize), and Zingiber officinale (ginger) (CABI- CPC, 2021). Symptoms: